A boyfriend once called Leslie Jamison "a wound dweller." This is one of many personal morsels she shares in her virtuosic book of essays, The Empathy Exams, in which she intrepidly probes sore spots to explore how our reactions to both our own pain and that of others define us as human beings. Jamison notes with concern that ironic detachment has become the fallback in this "post-wounded" age that fears "anything too tender, too touchy-feely." The Empathy Exams presents a brainy but heartfelt case for compassion even at the risk of sentimentality.

The Harvard and Iowa graduate — currently in the English doctoral program at Yale — reminds us that the word empathy derives from the Greek em, meaning into, and pathos, meaning feeling – amounting to "a penetration, a kind of travel." Her book's epigraph, from Terence's Latin motto, "I am human: nothing human is alien to me," announces that she considers nothing too strange for her consideration.

Determined to penetrate wildly divergent venues of extreme emotion, Jamison's inquiry is a travelogue of sorts, taking us to a brutal ultramarathon through the "briar-bearded hills" of Tennessee and a low-security prison in West Virginia. Occasionally — as in her explorations of a Los Angeles neighborhood that's been ravaged by gangs, or a Mexican border crossing — her forays fall flat, unable to escape a whiff of poverty tourism despite her awareness of the dangers of voyeurism.

But more often, Jamison stitches together the intellectual and the emotional with the finesse of a crackerjack surgeon. In the powerful title essay, she describes a job working as a "standardized" or simulated patient. For $13.50 an hour, prompted by 10-12 page scripts, Jamison "plays sick" to help train medical students, who are required to diagnose and respond to her maladies. Afterwards, she evaluates their performance from a checklist, including, most importantly, their show of compassion.

This somewhat bizarre occupation was featured to brilliant comic effect in the outlandish opening story of Alan Bennett's recent collection, Smut. But Jamison's concern is serious, focused on the reactions her medical acting elicits rather than the dissembling involved in prompting them. And by deftly interweaving an account of a two-month period during which she underwent both an abortion and heart surgery, she takes her essay to a higher level. The dismissive, uncaring cardiologist treating Jamison's arrhythmia would surely flunk an empathy exam, while her boyfriend initially receives just a barely passing grade.

Jamison is a pro at reading deeply, whether into wide-ranging sources such as Susan Sontag, Virginia Woolf, Lucy Grealy, Frida Kahlo, James Agee and Caroline Knapp, or into her personal experiences. She writes that since entering graduate school, "I looked back at my own life like text." Fortunately, she largely avoids abstruse pedagogy, although — striving to bring a measure of objective understanding to another painful, frightening experience — she fascinatingly applies academic methodology to an analysis of being punched in the face by a mugger in Nicaragua.

Jamison's attraction to the offbeat and dangerous keeps us agog. She attends a conference of Morgellons disease – characterized by the sensation of crawling insects and the extrusion of unidentifiable fibers from the skin — which doctors don't recognize as a disease and the CDC has labeled an "unexplained dermopathy." After making a concerted effort to mask her skepticism while talking with various attendees, she concludes, "This isn't an essay about whether or not Morgellons disease is real. That's probably obvious by now. It's an essay about what kinds of reality are considered prerequisites for compassion. It's about this strange sympathetic limbo: Is it wrong to call it empathy when you trust the fact of suffering, but not the source?"

Jamison's manifesto reaches its apotheosis in two essays, "In Defense of Saccharin(e)" and the multi-part "Grand Unified Theory of Female Pain." After flagging the prevalence of wounded women in literature, from Miss Havisham to Blanche DuBois, she argues eloquently for "the possibility of representing female suffering without reifying its mythos." She also points out: "I'm not the first voice to call for sentimentality in the wake of postmodern irony. There's a chorus. There's been a chorus for years. Once upon a time, it was directed by David Foster Wallace. Now it's directed by his ghost."

With The Empathy Exams, Jamison has seized the baton, and the result is a soaring performance on the humanizing effects of empathy.